cycloprodigiosin and Breast-Neoplasms

The effects of cPrG x HCl and epirubicin on the suppression of cell growth were examined on human breast cancer cell line (MDA-MB-231). Either cPrG x HCl or epirubicin alone showed a tumor growth inhibition in a time- and dose-dependent manner, however, the combinatory use of cPrG x HCl together with epirubicin resulted in prominent synergistic effects on the breast cancer cells. In the in vitro studies, the combinatory use of these two drugs accelerated apoptotic cell death as revealed by morphological changes as well as by the appearance of subG1 population by flow cytometry. In addition, confocal microscopy revealed that the accumulation of epirubicin in nucleus increased apparently when cPrG x HCl were present. In the in vivo assay, nude mice bearing xenografted tumor cells received 4 weeks of intraperitoneal administration of cPrG-HCl and epirubicin. After 12 days, the combinatory treatment significantly suppressed the tumor growth compared to the controls. The TUNEL staining revealed that tumor cells in cPrG x HCl plus epirubicin-treated mice exhibited a higher apoptotic rate. In addition, 31P-NMR studies on the xenografted tumor revealed that cPrG x HCl lowered tumor pHi (below pH 6.9). while it did not affected muscle pHi. No pathological changes were observed in any intrinsic organs and the serum alanine aminotransferase levels remained within normal limits among the groups. These results suggest that the combinatory use of cPrG x HCl and epirubicin may be useful for breast cancer therapy.

Topics: Animals; Antibiotics, Antineoplastic; Apoptosis; Breast Neoplasms; Cell Division; Dose-Response Relationship, Drug; Drug Synergism; Epirubicin; Female; Flow Cytometry; Humans; In Situ Nick-End Labeling; Indoles; Injections, Intraperitoneal; Magnetic Resonance Spectroscopy; Mice; Mice, Nude; Microscopy, Confocal; Phosphorus Radioisotopes; Pyrroles; Transplantation, Heterologous; Tumor Cells, Cultured

The effect of cycloprodigiosin hydrochloride (cPrG.HCl), a H+/Cl- symporter, on five human breast cancer cell lines (KPL-1, T-47D, MCF-7, MKL-F, and MDA-MB-231), a human breast epithelial cell line (HBL-100), and a human fibroblast cell line (WI-38-40) was examined. cPrG.HCl inhibited the growth of all five breast cancer cell lines (IC50: 0.46-0.62 microM) and slightly inhibited HBL-100 and WI-38-40 cell growth (IC50: 1.75 microM and 2.26 microM respectively). cPrG.HCl treatment in KPL-1 cells increased the pH of acidic organelles, decreased intracellular pH, and caused apoptosis, which was confirmed by the appearance of a sub-G1 population by flow cytometry and DNA fragmentation. In addition, cPrG.HCl-induced apoptosis was strongly suppressed by imidazole, a cell-permeable base, suggesting that intracellular acidification was essential for the apoptosis. Further, cPrG.HCl treatment up-regulated Bax and Bak expression, down-regulated Bcl-2 expression, and activated caspase-3. Therefore, the intracellular acidification by cPrG.HCl treatment suppressed the growth of human breast cancer cell lines by inducing apoptosis.

Topics: Antiporters; Apoptosis; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein; Breast Neoplasms; Cell Cycle; Cell Division; Humans; Hydrogen-Ion Concentration; Immunosuppressive Agents; Indoles; Membrane Proteins; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Proton-Translocating ATPases; Pyrroles; RNA, Messenger; Signal Transduction; Tumor Cells, Cultured; Vacuolar Proton-Translocating ATPases